What is alfalfa meal? Is it a good fertiliser?

By Joe Barrington, founder of Dr Forest · Published May 2026 · Updated 6 November 2026

Quick answer. What is alfalfa meal? It's dried, milled lucerne (alfalfa), and yes, it's a good fertiliser if you want a gentle, slow one. It's roughly 2.5 to 3% nitrogen, with about as much potassium and calcium but little phosphorus or magnesium. Soil microbes release it over several weeks once the soil warms, so it won't scorch, and it won't rescue a hungry plant in a hurry either. Use 100 to 150 g per m² in mid-spring. I use it in my blends rather than on its own.

Best in a blend

I use alfalfa in every NPK feed I formulate and blend, from the All Purpose 4-4-4 and Bloom 2-8-4 to the Tomato, Strawberry, Potato, Rose and Fruit & Veg feeds. It gives slow-release nitrogen with no peaks and troughs, so the plant gets a steady supply over the long term. It also brings a decent amount of available potassium and a very good spread of micronutrients, which are hard to get into an organic feed without reaching for sulphates. And it's high in carbon, which is good for soil health.

I don't use alfalfa meal on its own. Blended feeds, with other ingredients alongside, do better.

What is alfalfa meal?

Lucerne, which Americans call alfalfa, is a perennial legume grown for livestock and sometimes sown as a green manure. Like peas and clover, it fixes its own nitrogen from the air and stores it as protein in the leaf. The crop is cut, wilted and dried to about 10% moisture [3], then milled into meal or pressed into pellets like the Dr Forest Alfalfa Meal Pellets.

What is in a bag of it

Feed tables for dried lucerne give about 2.9% nitrogen, 3.1% potash (K₂O) and 3.1% calcium (as CaO), with only 0.6% phosphate (P₂O₅), plus trace manganese, zinc and copper [3]. So it feeds potassium and calcium as well as nitrogen. Those figures are for bone-dry material, so a bag at about 10% moisture reads a little lower, and batches vary: protein in nearly 15,000 analysed samples ran from 13.1% to 27.9% [3]. The Dr Forest pellets are declared at 2.5-0.3-2.

At the bed rate of 100 to 150 g per m², those pellets put down 2.5 to 3.75 g of nitrogen and 2 to 3 g of potash per square metre, for the soil to release over the following weeks.

Magnesium is the weak spot, at about one part to twelve of potassium [3]. If older leaves yellow between the veins, add kieserite, which gives magnesium without more potash.

Meal or pellets, and which acts faster

A pellet is pressed meal with no coating. It sits idle while dry, but once wet it swells, falls apart within days and then acts much like meal, so water pellets in after spreading. Pellets scatter evenly, don't blow about and store without caking.

How the nitrogen arrives

The nitrogen in alfalfa is locked in plant protein, so none of it reaches the plant until soil microbes break it down. Whether they release nitrogen or borrow it from the soil depends on the material's carbon-to-nitrogen ratio, with the switch at around 13 to 15. Alfalfa sits at 12 to 15, right on the line, and one study even found net lock-up from alfalfa meal, most likely down to a low-nitrogen batch [6]. A plant that's hungry now needs a high nitrogen feed that dissolves straight away.

Cold soil holds alfalfa back, because the microbes that release its nitrogen barely work until the ground warms, so spread it on warm, moist soil and go by a soil thermometer rather than the calendar. The same March stall hits every organic slow-release fertiliser, not just alfalfa.

The carbon that stays behind

Ash is only about 12% of the dry weight, so close to 90% of it is organic matter, and nearly 29% is crude fibre that breaks down slowly and feeds soil life [3]. In an intensive organic greenhouse trial, supplying half or all of the nitrogen as alfalfa meal cut nitrogen losses and raised soil nitrogen and carbon, and earthworm, bacteria and fungi numbers, while yields in the soil beds held up [2].

The growth hormone question

Buy alfalfa meal for the nutrition. Triacontanol, a leaf-wax alcohol, was first isolated from lucerne wax in 1933 [1], and it's a real plant growth regulator, used on crops across millions of hectares in Asia [5]. In a 2024 trial, potted tomatoes sprayed weekly on the leaves with purified triacontanol carried 37 to 50% more flowers and gave 28% more fruit by weight, though each fruit was 16% lighter [4].

As for the triacontanol in a bag of alfalfa, I don't believe the amount does anything substantial. For results that impress you need it concentrated in a liquid, such as Brix+, which contains triacontanol. You know it when you've used it.

Triacontanol doesn't dissolve in water, so alfalfa tea won't carry much of it. The tea method is in alfalfa for roses.

How much to use, and when

Where	Rate	When
Beds and borders	100 to 150 g per m²	Mid-spring, once the soil has warmed, worked into the top few centimetres
Side dressing beds	100 to 150 g per m²	Every 4 to 6 weeks through the growing season, stopping by late August
Tomatoes and cucumbers	50 to 100 g per plant	At planting, and again at first flower set, around the drip line
Potting and soil mixes	5 to 10 g per litre (5 g in seed compost)	Mixed in at potting or before sowing, then top-dressed monthly in pots
Compost heap	A light sprinkling between layers	As you add woody, carbon-heavy material

Apply to moist soil, scratch it in and water it in. Rose rates are in my alfalfa for roses guide, lawn rates in alfalfa for lawns, and the method in my guide on how to top dress.

Alfalfa carries about 2.2% calcium (3.1% as CaO) [3], so heavy doses every year add to ground that often has plenty already. Store it dry, and wear a dust mask when spreading meal.

Where it fits, and where it does not

Use it on hungry leafy crops and repeat-flowering shrubs: brassicas, squash, sweetcorn, roses, clematis, dahlias, and beds you refill every year. It suits a living soil approach, and if you're weighing it against rock dust, seaweed meal and the rest, my guide to organic dry amendments sets them side by side. Skip it on ericaceous beds, because of the calcium, and don't lean on it as an emergency feed.

Related: High Nitrogen Fertiliser 13% N · Dr Forest range

Common questions

What is alfalfa meal used for?

It is used as a slow-release organic nitrogen feed and soil improver, mostly on hungry leafy crops, roses and other repeat-flowering shrubs, and in potting mixes. A struggling plant that needs feeding now wants a soluble feed.

What is the NPK of alfalfa meal?

Dried lucerne averages roughly 2.9% nitrogen, 0.6% P₂O₅ and 3.1% K₂O, plus about 3.1% CaO and 0.35% MgO. Labels are lower: the Dr Forest pellets are declared at 2.5-0.3-2.

Alfalfa meal or alfalfa pellets, which is better?

Neither: they are the same material, and wet pellets behave like meal. Pellets spread more evenly and store better.

How much alfalfa meal do you use per square metre?

Work 100 to 150 g per square metre into a bed in mid-spring, once the soil has warmed. In potting mix, use 5 to 10 g per litre.

Can I use horse feed alfalfa pellets in the garden?

Only if the bag is pure alfalfa with nothing added, so read the label. Feed pellets can contain molasses, oils or mould inhibitors, and mixes with grass or hay in them can carry persistent weedkillers such as aminopyralid.

Does alfalfa meal really contain a growth hormone?

It contains triacontanol, a real growth regulator, but its clear results come from purified sprays on the leaves. I don't believe the amount in alfalfa meal does anything substantial, so use it for the nutrition.

Will alfalfa meal burn plants?

Not at the rates above, because the nitrogen is released slowly. The realistic risk on repeat use is calcium build-up on limed ground.

How long after applying alfalfa meal can I sow seed?

You don't need to wait: mixed into seed compost at 5 g per litre, it's gentle enough to sow into straight away. In beds it's safe at transplanting, so plant out as soon as it's worked in.

Joe Barrington, founder of Dr Forest in Stockport. Joe formulates and blends his own feeds, including All Purpose 4-4-4 and Bloom 2-8-4, and stocks bought-in products alongside them.

Sources cited

1. Chibnall, A.C., Williams, E.F., Latner, A.L. & Piper, S.H. (1933). The isolation of n-triacontanol from lucerne wax. Biochemical Journal 27(6): 1885 to 1888. doi.org/10.1042/bj0271885
2. Giard-Laliberté, C., Madore-Millette, G., Pelster, D.E., Messiga, A.J., Dessureault-Rompré, J. & Dorais, M. (2026). Improving ecosystem services with alfalfa meal in highly intensive organic soil-based and soilless greenhouse systems. Agronomy for Sustainable Development 46(3): 40. doi.org/10.1007/s13593-026-01112-y
3. INRAE, CIRAD, AFZ & FAO. Alfalfa, dehydrated (lucerne, Medicago sativa): nutritional tables. Feedipedia. feedipedia.org/node/275
4. Manai, M. et al. (2024). Phenotypical and biochemical characterization of tomato plants treated with triacontanol. Scientific Reports 14: 12096. doi.org/10.1038/s41598-024-62398-0
5. Naeem, M., Khan, M.M.A. & Moinuddin (2012). Triacontanol: a potent plant growth regulator in agriculture. Journal of Plant Interactions 7(2): 129 to 142. doi.org/10.1080/17429145.2011.619281
6. Reid, K. & Morcom, T. (2023). Nitrogen mineralization from organic fertility sources. Perennia Food and Agriculture. ofcaf.perennia.ca